Process of making camphor from isoborneol.



riruTnn sTaTns iexTnnT orrrcn CURT PHILIPP, 0F DRESDEN, GERMANY, ASSIGNOR Tt) CHEMISCHE FABRXK VON HEYDEN AKTIENGESELLSCHAFT, OF DRESDEN, GERMANY.

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Specification of Letters Patent.

Patented April 2, 1907.

Application filed may 4. 1906. Serial No. 315,202.

To all whom it may concern:

Be it known that 1, Gear PHILIPP, a subject of the King of Saxony, and a resident of Dresden, Tieckstrasse 8, Kingdom of Saxony, German Empire, have invented new and useful Improvements in the Manufacture of Camphor from Isoborneol, of which the following is a specification.

Borneol and isoborneol when heated with concentrated nitric acid to to centigrade behave so differently that Tschugajew has founded on this fact an easy method of distinguishing them. (See Uhe'milcer-Zeittmg 1902, p. 1224.) Hesse, in the Ber'ichic der Deutschen Uhemischen Gesellschaft, 1906, p. 1144, has confirmed Tschugajews observations. According to this by heating borneol to 40 to 50 centigrade with concentrated nitric acid red vapors are produced and camphor is obtained, which precipitates on diluting with water. lsoborneol, on the contrary, produces with concentrated nitric acid at 40 to 50 centigrade neither red vapors nor camphor, but after precipitating with water a thick yellow oilwhich apparently contains nitrogen.

' lsoborneol behaves diiierently when boile with concentrated nitric acid. Bertram and 'Walbaum, in the Journal f'tir Pralctische Climate, vol. 49, p. 10, explain that isoborneol is oxidized to camphor when boiled with nitric acid. This reaction, however, cannot be applied in practice. Although vessels actualy exist wich will withstand for some time the working with boiling nitric acid, it is to be noted that the oxidation of isoborneol to camphor by boiling with nitric acid soon reaches explosive intensity and the yield becomes an insufiicient one. For the practical application it has therefore been proposed to oxidize the isoborneol to camphor by means of nitrous acid or of permanganate,

(German Patent 157,590,) or chlorin, (claim of German a plication 337,228 and 337,281,) or hypoc orites,(British Patent 2, 520, 1906,) or oxygen, (German Patent 161,523,) or ozone, (German Patent 161,306.) isoborneol can also be oxidized to'camphor by but converts it to a thick yellow oil, nitric acid containing even traces of nitrous gases 0x1- dizes isoborneol at this temperature to camhor in a reaction, which can be easily'reguated. it does not matter whether a nitric acid containing nitrous gases is applied or whether care is only taken that substances developing nitrous gases from nitric acid are present. It therefore is sufiicient, for example, that to the nitric acid or to the isoborneol to be oxidized, or to the mixture of both, small quantities of organic or inorganic substances are added, such as are oxidized by nitric acid while forming lower, oxy compounds of nitrogen. Such substances are, for example, hydrochloric acid, metals like copper, arsenious acid, or organic substances, such as amylum and borneol itself, 850. When startingirom an impure isoborneol already containing substances which can be oxidized by nitric acid-for example, borneolfurther substances of this kind need not of course be added. @nly very small quantities of nitrous gases or bodies producing same are necessary for starting the oxidation.

Example: Five grams sodium nitrite (NaNG are added to one hundred and twenty-five kilograms nitric acid of 1.4 specific gravity. Then twenty-five kilograms isoborneol are by portions stirred into the mixture. Spontaneous heat soon causes oxidation to begin. By exterior cooling and by regulating the supply of isoborneol care is taken that'the temperature does not rise above 40 centigrade. After the whole quantity of isoborneol is added stirring is continued until the development of nitrous gases has ceased. Thereafter the vessel is emptied, and the camphor nitrate floating on the acid is drawn oil. It then is decomposed by mixing it with water, and the precipitated camphor is filtered oil. it an isoborneol is used for oxidation containing small quantities of borneol or other substances which react with nitric acid, reducing it to lower oxy compounds of nitrogen, pure nitric acid maybe used, as stated before, which adding isoborneol to nitric acid below the" my invention I have signed my name,

boiling-point of the latter, taking care that presence of two witnesses, this 23d day of the reaction is brought about by the pres-- April, 1906.

ence of small quantities of lower oxy com- CURT PHILIPP. 5 pounds of nitrogen, substantially as and for Witnesses:

the purpose specified. PAUL E. SCHILLING,

In testimony that I claim the foregoing as g r PAUL AREAS. 

